Florida’s mangrove forests are on the move. Satellite images from the past three decades reveal that these diverse coastal ecosystems have crept up the state’s Atlantic coast thanks to rising winter temperatures.

To chart the expansion of these tidal zone–loving tropical trees, Smithsonian Environmental Research Center ecologist Kyle Cavanaugh and colleagues compared images taken by NASA’s Landsat satellites from 1984 to 2011. During this period, the area occupied by mangrove forests south of ...